Trouble in upgrading my device

Hi there,
for about 3 days i found difficulty in upgrading my device, it was Storm 9520 by Vodafone, i followed every step i knew bout upgrading OS and there were no difficulty. i back up, then wipe the device with BBSAK, the i installed the OS file and then i deleted the vendor xml. the loader could read the pin but after the process of JVM, the installation process couldn't be proceeded it was saying that there's no Os file available for the device, and a notice that there's a fatal error upgrading your device, i wonder what was wrong with that, for i never found such problem before in upgrading other devices.
I ran the cc cleaner, clean up my recycle bin, and the loader files 5.0.0.1077 by vodafone UK, and other loader files and i've tried to upgrade it in other pc without deleting the Vendor.xml, load it with vnbbutils, amd BBSAK but it's worthless cos the same things happen. in my curiousity i tried to downgrade my device Bold 9650 by verizon with the os 6.0.0.706 by sprint ( vendor have been deleted ), the same thing happened, and then i installed and load os 6.0.0.719 by verizon without deleting the vendor and succeeded. and the Storm 9520 is still in the error 507 condition:(
Please could anyone help me out with this problem, thanks before.

Thanks, I've read that tutorial, thanks a lot, but still could not load the os,but this morning i got it load, by installing another os file 9520/5.0.0.1077 without deleting the vendor, thanks a lot for your response,

Thanks, I've read that tutorial, thanks a lot, but still could not load the os,but this morning i got it load, by installing another os file 9520/5.0.0.1077 without deleting the vendor, thanks a lot for your response,

yes i do, but there's another problem come in the line, i tried to upgrade my friend's device ( Torch 9800 ) for OS 6.0.0.723, i backed up the device then i wiped it, then i installed the loader file and delete the vendor xml, the os couldn't b found !!
such weird things happen lately for 3 devices i tried to upgrade. i've uninstalled the BBDM and BBSAK and ran the cc cleaner on my laptop ( Assus Windows 7 ) but still it can be load, please give me any idea what should i do to my laptop, perhaps some program are missing. thank you.

yes i do, but there's another problem come in the line, i tried to upgrade my friend's device ( Torch 9800 ) for OS 6.0.0.723, i backed up the device then i wiped it, then i installed the loader file and delete the vendor xml, the os couldn't b found !!
such weird things happen lately for 3 devices i tried to upgrade. i've uninstalled the BBDM and BBSAK and ran the cc cleaner on my laptop ( Assus Windows 7 ) but still it can be load, please give me any idea what should i do to my laptop, perhaps some program are missing. thank you.